Control systems for effecting the timed actuation of a controlled device and methods therefor



Oct. 6, 1970 F. s. KAsPER `3,532,990

CONTROL SYSTEMS FR EFFEC'IING THE TIMED ACTUATION OF A CONTROLLED DEVICEAND METHODS THEREFOB Filed nec. 19. 196s 4 sheets-sheet 1 Oct. 6, 1970F. KAsPER 3,532,990

CONTROL SYSTEMS FOR EFFEC'IING THE TIMED ACTUATION OF A CONTROLLEDDEVICE AND METHODS THEREFOR Filed Dec. 19. 1966 4 Sheets-Sheet 2 Oct. 6,1970` F. s. KASPER 3,532,990

CONTROL SYSTEMS FOR EFFECTING THE TIMED ACTUATIDN OF A CONTROLLED DEVICEAND METHODS THEREFOR Filed Dec. 19. 1"'966 4 sheersneer s SCK E 5;@K .0|Z3 fyzyefzyn' M22/(45T @Qca/2 Oct. 6, 1970 F. S. KASPER CONTROL SYSTEMSFOR EFFECTING THE TIMED AGTUATI Filed Dec. 19. 1966 United States PatentO CONTROL SYSTEMS FOR EFFECTIN G THE TIMED ACTUATION OF A CONTROLLEDDEVICE AND METHODS THEREFOR Frank S. Kasper, Hazel Crest, Ill., assgnorto Amtron,

Inc., Midlothian, Ill., a corporation of Illinois Filed Dec. 19, 1966,Ser. No. 603,012 Int. Cl. G01n 27/00 U.S. Cl. 328-5 12 Claims ABSTRACT0F THE DISCLOSURE A control circuit accommodates both variable timedelays such as the time for an article to move from a first to a secondposition along a conveyor and fixed delays such as the turn-on andturn-off times for a spray gun or the like to effect a precisely timedoperation of the spray gun. First and second current generators areactuated by the presence of the article at the first position tocommence charging of a capacitor bank that in turn actuates the spraygun when a predetermined charge is accumulated. The first currentgenerator provides a current output proportional to the rate ofadvancement of the article and the second, which is operative for only aportion of the normal delay period, provides a combined current outputthat in effect anticipates the xed time and variable delays. Otherfeatures are disclosed.

This invention relates to control systems and more particularly tomethods of and systems for selectively and accurately controlling theactuation of one or more responsive instrumentalities in specic timedrelationship to other operational conditions of the unit or apparatuswherein the invention is employed.

Various industries have sought and are presently seeking reliable andefficient means for effecting the accurate control of responsiveinstrumentalities used in package fabrication, the deposition of coatingmaterials, receptacle filling, the injection of materials forconditioning products and the like. This demand is clearly exemplifiedin the packaging and coating fields wherein it is necessary toaccurately control the turn-on and turn-olf characteristics of gluedepositing devices and coating devices, respectively.

In this connection, it is essential in certain applications (eg. whencontrolling the discharge of glue along the sealing seam of a cartonbeing advanced relative to a glue discharge gun by a relatively highspeed conveyor,

when automatically depositing paint on advancing articles or whenfilling a stationary or moving receptacle with a material that issubject to a variable ow rate) to correlate the variable systemcharacteristics with the time lag involved in actually initiating andterminating the operation of the responsive device. In effecting suchcorrelation, the system must take into account the time delaycharacteristics of the unit as Well as variations in such delaycharacteristics that result from system operation. Such correlation isparticularly important in automatic spray coating systems, for example,to insure that the operation of the spray coating device is properlyinitiated as the article to be coated (or a segment thereof) is broughtinto alignment with the device and that the operation is terminated asthe article completes its pass relative to the coating device. It willbe appreciated that substantial amounts of coating material are Wastedif the selective actuation of the spray coating device is not accuratelycontrolled. Such waste problems and added expense are similarly incurredin the packaging and article filling elds. That is, if the responsivedevices employed in package sealing and article lling operations are notPatented Oct. 6, 1970 f, ICC

similarly controlled with substantial accuracy, both the loss ofmaterial and product output results.

The problems discussed above are faced by other industries and areencountered in many instances wherein it is important to accuratelycontrol the actuation of a responsive device at a precise period of timeand t0 promptly terminate its operation after the function to beperformed by the device has been concluded.

It is an object of the present invention to provide improved systems forand methods of controlling the operation of responsive devices inproduction apparatus and the like.

Still another object of the present invention is to provide controlsystems cap-able of accurately and reliably dictating the actuation anddeactuation of responsive devices in accordance with pre-establishedoperational patterns.

An additional object of the present invention resides in the provisionof systems for controlling various responsive devices in productionapparatus or the like so as to reliably compensate for any delayedresponse characteristics of such devices irrespective of othervariations in the operation of the apparatus.

A further object of the present invention resides in the provision ofcontrol systems for dictating the operation of responsive devicesemployed in production apparatus or the like, which control systems havethe necessary versatility to `be adapted for a variety of applicationsat relatively low cost and Without substantial modification in the basicfunctional characteristics thereof.

Other objects and advantages of the present invention will becomeapparent from the following description of one preferred embodimentthereof particularly when considered in conjunction with theaccompanying drawings wherein:

FIG. 1 is a diagrammatic representation of a control system embodyingthe features of the present invention;

FIG. 2 is a block diagram of the major components of the system asdepicted in FIG. l;

FIGS. 3, 4, and 5, when assembled as shown in FIG. 6, illustrate apreferred embodiment of the control system in detailed schematic form;and

FIG. 7 is a graphical representation of the compensated control functionof the system of the present invention.

Referring generally to the drawings, the present invention is directedto methods of and systems for controlling the selective actuation of aresponsive device or devices during discrete phases of the operating-cycle of the apparatus employing same. Without in any sense limitingthe versatility of the invention, its general character and operationcan perhaps best be appreciated if consideration is given to the use ofthe system with a particular type of production apparatus. Morespecifically and considering the application of the invention to apackaging facility, FIG. 1 of the accompanying drawings diagrammaticallydepicts the system when controlling the automatic application of glue ora similar adhesive substance to a carton being processed along aconveyor line.

In this connection, the numeral 10 represents a suitable transfer deviceor conveyor whereon an article 11 is disposed so as to be advanced inthe direction of the arrow (Le. from left to right). As the article 11is advanced relative to the location A, the presence of the article issensed and, in response to this sensing function, a signal istransmitted by the transducer and supplied to a control circuit 12. Theoutput of the control circuit 12 contributes to the control of anactuating means 13 which in turn dictates the operation of a responsivedevice positioned at location B. The responsive device at location Bperforms the desired function of applying glue or adhesive material to aselected portion of the advancing article 11.

In addition to the signal supplied from the sensing transducer atlocation A, the control circuit 12 is also provided with an outputsignal from a suitable speed monitoring means 14 is indicative of theadvancing rate of the conveyor and, therefore, of the article 11.Similarly a signal is supplied to the control circuit from anindependent signal source 15, which signal is indicative of the fixeddelay characteristics of the system components. That is, the signal fromthe source reiiects the turn-on/turnoli time delay characteristics ofthe glue gun and other delay characteristics inherent in the operationof the system components.

An auxiliary control circuit 16 operates essentially in parallelrelationship with the control circuit 12. As shown, the control circuit16 is also provided with a signal from the article sensing transducer atlocation A, with an advancing rate signal from the conveyor speedmonitoring mechanism 14, and with a delay characteristic signal from thesource 1S. The output of this auxiliary control circuit 16 is suppliedto the actuating means 13 along with the output from the control circuit12. The cooperative action of the control circuits 12 and 16, inresponse to the input signals supplied thereto, results in the actuatingmeans 13 being rendered effective so as to initiate the functionperformed on the article 11. In accordance with the invention, this isaccomplished at the precise time that a designated segment of thisadvancing article is in alignment with the output of the glue gun orapplicator provided at location B. These coacting control circuits alsodictate when this function (i.e. the application of glue to a designatedsegment of the article 11) is terminated after the article has advancedsufficiently along its path of travel relative to location B. In theevent that the conveyor 10 is subjected to speed variations, thecooperative action of the control circuits 12 and 16 results in anadjustment being made in the output signal supplied to the actuatingmeans 13. Thus suitable compensation is made for the fixed timecharacteristics of the system in direct correlation to any transientvariations in the advancing rate of the article 11.

An appreciation of the detailed functioning of the system of the presentinvention will be enhanced if the responsive device is considered fromthe analogous point of view that its operation is dictated in directresponse to the rate at which energy is supplied to the actuating means13 (i.e. as a result of the combined outputs of the control circuits 12and 16). Thus under constant article transfer rate conditions, thecombined output energy rate of the control circuits 12 and 16 isdirectly related to the fixed relay characteristics of the system.However, when the advancing rate of the article is subject to transientvariations, these control circuits operate in mode which reflects suchspeed changes and correlates such speed changes to the time delaycharacteristics so that product output of the controlled apparatus isnot adversely affected. Accordingly, if an increased advancing rate issensed (i.e. dictating that the glue applicator should be actuatedearlier in the operating cycle) the combined energy output rate of thecontrol circuits 12 and 16 is increased. On the other hand, if systemconditions dictate that the actuation of the responsive device should bedelayed (i.e. reflecting a decreased article advancing rate), thecombined energy output rate of the control circuits 12 and 16 isreduced.

In a functional sense, this coacting operation of the control circuits12 and 16 suggests that the compensating adjustments for the delaycharacteristics (i.e. which occur when speed variations are sensed)result from operation in a negative time mode. That is, when theconveyor speed is varied, the control system reacts as though the fixeddelay period of response was anticipated and began timing out evenbefore the article was sensed at location A (i.e. before the start ofthe operating cycle). Thus and notwithstanding a variation in thearticle advancing rate and assuming the same fixed delay characteristicsof the system, the responsive device is rendered effective at the properinstant and remains operative for a period of time necessary to yield aglue bead substantially identical to a glue bead that would be laid downon an article advanced relative to the same glue gun without beingsubject to advancing rate variations. In the illustrated embodiment,these unique functional characteristics of the system, whereby the fixeddelay is anticipated as depicted in FIG. 7, are achieved electronicallyas will become apparent from the circuits of FIG. 2 and FIGS. 3-5.

Referring first to FIG. 2, a preferred embodiment of the system of thepresent invention is shown as including a power supply 20 that suppliesthe necessary operating energy to the other components of the systemthrough suitable circuit means 20a, 20h, 20c, 20d, and 20e. An articlesensing transducer 21 (i.e. a light source and associated photocell) isconnected in circuit with an amplifier 22, the output of which issupplied to a timer control circuit 23. The timer control circuit 23 iselectrically connected in circuit with a speed and fixed time responsivecircuit 24 by means of individual delay-function and duration-functioncircuits 26 and 27, respectively. In addition, the output of the timercontrol circuit 23 is connected to a solid state switching circuit 28which in turn dictates the operative state of a responsive device 29 (cg. a glue applicator, spray coating device, article filling dispenseretc.). As shown, the speed and fixed time responsive circuit 24 is alsosupplied with the output of a rate monitoring device (e.g. a tachometergenerator) 31.

Considering the aforedescribed system in somewhat greater detail inrelation to FIG. 2, the transducer 21 senses the presence of anadvancing article 11 at location A as represented in FIG. l. The outputof the transducer is fed to the amplifier circuit 22 and is supplied bysuitable circuit means 22a to the input of the timer control circuit 23.This sensing of the advancing article by the transducer 21 initiates theautomatic functioning of the control system so that 1) the responsivedevice is not triggered into operation until the desired portion of thearticle to be treated thereby is suitably aligned with the responsivedevice and (2) the responsive device is operated for the preciseinterval necessary to complete the desired function. However, it shouldbe understood that for any given application certain preselectedconditions will be established in the control circuit so that therequirements of the particular application are accurately reflected inthe automatic operation of the system.

In accordance with the present invention (and as shown more specificallyin FIGS. 4 and 5), the timer control circuit 23 is preferably comprisedof two interrelated and coacting timer modules which are alsooperatively associated with the delay-function and duration-functioncircuits 26 and 27 as well as with the circuit 24. Preferably, theinterrelated and coacting timer modules of the timer control circuit 23correspond to those disclosed and claimed in the copending applicationof the common assignee Ser. No. 400,322 which was filed on Sept. 30,1964. As fully described in this copending application, each of thetimer modules of the timer control circuit 23 is preferably a solidstate timing circuit that employs transistorized bistable multivibratorand unijunction firing circuits which cooperatively function to producean output signal of preselected duration.

One of the timer modules of the timer control circuit 23 in conjunctionwith the delay-function circuit 26 and a portion of the responsivecircuit 24 is employed to actuate the responsive device 29 when adesignated segment of the advancing article is properly positioned withrespect to the output of the device. The second of the timer modules,which is actuated in response to the deactuation of the first timermodule, similarly coacts with the duration-function circuit 27 and stillanother portion of the responsive circuit 24 to precisely control theperiod during which the responsive device 29 is rendered effective.

In operation of the timer control circuit 23, the sensed article signaloutput from the amplifier 22a effects a modification in the conductivestate of the multivibrator circuit associated with the delay-periodtimer module. This response of the timer module and the correspondingoutput from the timer control circuit 23 triggers the start of the delaytiming cycle as a result of variations in the conductive state of thecomponents forming the delay function circuit 26 and portions of theresponsive circuit 24. As previously outlined, this delay timing cyclecorresponds to the period of time required to allow a selected portionof the article 11 to be advanced into proper position with respect tothe responsive device 29 after being sensed at the location A (FIG. 1).

The responsive circuit 24 preferably employs dual current generatingcircuits, as shown more specifically in FIG. 5. The outputs of thesedual current generating circuits have independent and direct effect upon(1) the period during which the operation of the responsive device isdelayed and (2) the period for which the responsive device is renderedeffective. As previously outlined, this control is effected so that thedelay characteristics of the system components do not adversely affectthe performance of the system, irrespective of variations in theadvancing rate of the article as it is advanced toward and relative tothe responsive device 29. Thus, the dual current generating circuitwhich comprise the responsive circuit 24 translate the usable advancingrate information derived from the rate monitoring device 31 intocompensating control signals that are directly reflected in theoperation of the timer control circuit and, ultimately, in the actuationof the solid state switching network 28 that controls the responsivedevice 29.

Considering the dual circuit characteristics of the responsive circuit24 in somewhat greater detail, the delay period current generatingcircuitry thereof is initiated into operation along with thedelay-function circuit 26 in response to the initiation of the delayperiod timing cycle of the timer control circuit 23. More specifically,the delay period current generating circuitry of the responsive circuit24 is basically comprised of two subcircuits. The conductive state ofthese two subcircuits is directly correlated to the advancing rate ofthe article as reflected by the output of the rate monitoring device 31.However, one of these subcircuits is additionally conditioned tofunction in relation to the predetermined lixed time responsecharacteristics of the system components. As is hereinafter morespecifically described, these subcircuits coact so as to yield thenecessary energy output rate that will directly influence thetermination of the delay period function of the timer module circuit 23through cooperative action with the delay function circuit 26.

In this latter connection, the current output of the delay periodportion of the responsive circuit 24 consists of (l) a current componentrelated both to the output of the xed delay time subcircuit and anysensed variable speed characteristics of the system and (2) a currentcomponent which is proportionately related to the variable speedcharacteristics, if any, detected in the advancing rate of the article.The current component that is related exclusively to the advancing rateof the article is utilized in the output of the responsive circuit 24until the entire delay period is concluded. However, the currentcomponent related to the fixed delay time characteristics, as well asthe advancing rate of the article, is produced and contributes to thetotal current output of the responsive circuit 24 only during adesignated portion of the delay period cycle. This designated portion ofthe delay period cycle is preselected, as hereinafter described indetail, so as always to be less than the minimum delay period that maybe established for the particular application wherein the system isoperating.

Irrespective of the variable characteristics of the system as influencedby the advancing rate of the article, the fixed delay time circuitryproduces a current output for the designated portion of the delayperiod. However, the magnitude of the current produced by thissubcircuit varies in accordance with and is proportionately related tothe output of advancing rate subcircuit. Thus, the control system of thepresent invention, through the coaction of these subcircuits, insuresthat within at least a preselected period of time, compensation isprovided for variations occurring in the system operation. Accordingly,at the conclusion of the delay period, the duration of which is directlyinfluenced by the combined outputs of the subcircuits forming theresponsive circuit 24, the article or a designated segment thereof isproperly positioned as desired with respect to responsive device 29 sothat the desired function can be initiated.

The termination of the delay cycle of the system is effected as a resultof a further alteration in the conductive state of the delay periodtimer module of the timer control circuit 23, as hereinafter morespecifically described. Concomitant with this alteration in theconductive state of the delay period timer module, the duration periodtimer module of the control circuit 23 is rendered effective. It is thislatter response of the overall timer control circuit 23 which actuallytriggers the solid state switching network 28 so as to render theresponsive device 29 effective.

In a manner generally similar to the aforedescribed cooperative actionbetween the delay period timer module of the control circuit 23, thedelay function circuit 26 and the delay period current generatingcircuitry of the responsive circuit 24, the duration period timermodule, the circuit 27 and the duration period current generatingcircuitry of the circuit 24 coact to provide an advancing ratecompensated period of operation for the responsive device under theinfluence of the solid state switching network 28. In this connection,the major distinction between the cooperating delay period circuitcomponents and the cooperating duration period circuit componentsdepends on the relative turn-on and turn-off response characteristics ofthe device 29. That is, depending upon whether the turn-on and turn-offtime response characteristic of the device 29 differ or are the same,additional subcircuits of the responsive circuitry 24 are brought intoplay as hereinafter described. In any event, upon the conclusion of thecompensated or uncompensated duration period cycle, the conductive stateof the duration period timer module is altered to deactivate the solidstate switching netwiork and thus conclude the desired operation of theresponsive device 29 and the entire system is conditioned for subsequentcycles of operation.

Referring now to the detailed schematic illustration of a preferredembodiment of the control system contemplated by the present invention,the control system may be selectively operated in a more conventionalmanner without utilizing the supplementary current generatingsubcircuits of the responsive circuit 24. Moreover, the power supply andvarious of the conventional networks employed in the disclosedembodiment are merely illustrative of one form of circuit suitable foruse in accordance with the present invention. Accordingly, the followingdescription of the detailed circuit is directed primarily to thosefeatures of the control system which contribute to the compensatingoperation of the circuit 24 in conjunction with the circuits 23, 26, 27,and 28.

The power supply 20` preferably includes a pair of input transformers41a and 41h. As hereinafter more fully described, the input transformer41a supplies a rectifier network associated with the circuit 24 (FIG.5). Similarly, the input transformer 4117 drives a bridge rectiiier 42,and the output of the bridge rectier is supplied to a pair of seriesregulators 42a and 42h that utilize a Zener diode '42C for a referencepotential. The series regulator 42a serves as a reference source to apower series regulator 43 as well as to the series regulator 4219. Theregulator 42b supplies a regulated operating voltage to a light source21a which, along with a photocell 2lb constitute the transducer 21. Theoutput of the power series regulator 43 is coupled to a conductor 45that supplies the remaining circuits of the control system with thenecessary operating potential. In addition, the output of the regulator43 is supplied to a potentiometer 43a so that a selectively adjustablebiasing potential is provided at the base-emitter junction of an NPNtransistor 44 in the amplifier network 22.

With more specific reference to the amplifier 22, this network ispreferably a photo amplifier that is connected to the output of thetransducer 21. Preferably, the photocell 2lb and light source 21a thatform the transducer 21 are positioned relative to the conveyor 10 in theusual manner so as to be interrupted by an advancing article. Inresponse to such interruption and a corresponding change in theresistance of the photocell 2lb in the base of the transistor 44, theamplifier network 22 produces an output signal in the collector circuitof a PNP transistor network 46 that forms the output stage of theamplifier 22. This output signal is supplied through a couplingcapacitor 47 to the input of the timer control crcuit 23.

As generally outlined above, the timer control circuit 23 correspondssubstantially identically to that disclosed and claimed in theaforementioned co-pending application, Ser. No. 400,322. Preferably, thecontrol circuit 23 employs two timer modules 48 and 49. As hereinaftermore fully described, the operation of the timer module 48 is related tothe delay function of the control system, whereas the timer module 49functions in conjunction `with the duration circuitry of the responsivenetwork 24 to produce an output signal that controls the actuation ofthe switching network 28 (FIG. 3). Referring more specifically to FIGS.4 and 5, the timer module 48 preferably includes a bistablemultivibrator 51 formed by a pair of PNP transistors 51a and 51b. Inaddition, the timer module 48 includes an amplifier network formed by aPNP transistor 52 and its related circuit components, as well as aunijunction firing circuit 53. In a normal or quiescent state ofconduction, the transistor 51a of the multivibrator is renderedeffective and the unijunction firing circuit is conditioned to initiatea timing cycle. That is, the unijunction circuit 53, in conjunction withthe circuit 24 (FIG. 5) and the delay function circuit 26 (FIG. 4),responds to an output signal from the amplifier 22 that is coupled tothe base of the normally nonconductive transistor Slb, which is therebyrendered conductive, to initiate the delay cycle during which theconveyor aligns an advancing article (or a selected portion thereof)with the responsive device 29.

The timer module 49 is substantially identical to the module 48 andincludes a bi-stable multivibrator 56 formed by a pair of PNPtransistors 56a and 56b. In addition, the module 49 includes anamplifier network 57 and a unijunction firing circuit 58. The amplifier57 is normally in a nonconductive state. However, this circuit respondsto an alteration in the operative condition of the multivibrator 56 toprovide an output signal that is supplied to and triggers the operationof the solid state switching network 28 so as to effect the controlledactuation of the responsive device 29. As with the unijunction firingcircuit 53, the circuit 58 cooperates with the circuit 24 and theduration function circuit 27 to ensure that the solid state switchingnetwork 28 and, therefore, the responsive device 29l are renderedeffective for the desired period of time to effect the controlledfunction dictated by the system.

Considering now the responsive circuit 24, specific reference should bemade to FIGS. 4 and 5. As shown, the circuit 24 includes a delay network61 that is formed by a primary current generating circuit 61a, asecondary current generating circuit 61h, and a timing circuit 61c. Ashereinafter described, the timing circuit 61C dictates the operation ofthe secondary current generating circuit in conjunction with the primarycurrent generating circuit. The responsive circuit 24 also includes asimilar dual current generating circuit or duration network 62 that isformed by a primary current generator 62a, a secondary currentgenerating circuit 62b, and a timing circuit 62C. The networks 61 and 62are employed to compensate for the fixed delay characteristics of theoverall system components and for variations in the advancing rate ofthe article as detected in the output of the tachometer generator 31(FIG. 4).

Depending on the relative turn-on and turn-off delay characteristics ofthe responsive device 29, one or more of the secondary circuits 61b and62b and/or timing circuits 61c and 62C are selectively utilized in theresponsive network 24 to compensate for these characteristics, alongwith the aforedescribed variations in the advancing rate of the article.Moreover, in the particular instance when the turn-off delay time of theresponsive device 29 is less than the time required to initiate theoperation of the same device, a supplementary current shunting network64 is also employed in the responsive network 24 while at the same timethe secondary current generator 62b is rendered ineffective.

Various of the circuits which are selectively employed in the responsivecircuit 24 to compensate for fixed and variable delay conditions arearranged to be selectively switched in or out of this circuit, ashereinafter more fully described. However, as will be understood bythose skilled in the art, the responsive circuit can be constructed soas to be suited for a particular application and/or for controlling aresponsive device having given characteristics. This approachsubstantially simplifies the circuit 24 since the switching networks andsupplementaary circuits not essential for that particular applicationare eliminated.

Considering the network 24 in somewhat greater detail, the primarycurrent generators 61a and 62a are normally in a conductive state. Thatis, under quiescent conditions the PNP transistors that form thesecurrent generators are forward biased, and, for example, a path forcurrent through the collector of the transistor 61a is defined by aconductor 66 and the emitter-base one junction of the unijunction 53 inthe first timer module 48. A similar circuit for current flow throughthe collector of the transistor forming the primary current generator62a is completed through the unijunction circuit 58 of the second timermodule 49 when the control system is in a normal or quiescent state ofconduction.

Considering the circuits of FIGS. 4 and 5 in somewhat greater detail, abridge rectifier 71 is connected to the input transformer 41a and incircuit with a filter network 72 and a series voltage regulator 73. Theoutput of these circuits produces a positive voltage at a junction 74a,with a somewhat lower positive potential being similarly developed at ajunction 74b as a result of the voltage drop that is developed acrossthe diode 75. This positive potential along with a negative biasingpotential supplied to a terminal 24a through the conductor 45 conditionsthe circuit 24 so that both fixed time and speed compensated currentgenerating functions are selectively performable in response to theproduction of an output signal by the amplifier 22. In addition, thevoltage developed at the junction 74b is used as a reference potentialfor the tachometer generator 31 to insure that adequate operatingvoltage is provided to the unijunction circuis 53 and 58.

When the turn-on and turn-off delay characteristics of the responsivedevice 29 are identical, the switches 77a, 77b and 77e are innormally-open condition, as is the switch 78a. Under thesecircumstances, the responsive circuit 24 is comprised of the primary andsecondary current generating delay networks 61a and 61b, the primarycurrent generating duration network 62a, and the timing circuit 61C.Preferably, the base of the primary current generating transistor isconnected through a current limiting resistor 81 and a conductor 82 to aswitch contact 84a. The switch contact 84a and a second switch contact84h are utilized to select the mode of operation for the responsivecircuit 24. That is, position of these switches dictates whether or notthe responsive circuit operates in a mode such that it will compensatefor variations inthe advancing rate of the article.

In the positions shown in FIG. 4, the switches are set to properlyrespond to such variationsin accordance with the preferred mode ofoperation of the present invention in most applications. Morespecifically, the switch 84a completes a circuit to a potentiometer tap86 which, along with a conductor 87, provides the output of thetachorneter generator 31 to the base circuits of the PNP transistorsthat form the primary current generators 61a and 62a. As shown, theconductor 87 is connected to a temperature compensating diode 90. Sincethe output of the tachometer generator is directly related to thearticle advancing rate, the voltage applied to these base circuits issimilarly proportional to this advancing rate.

With further reference to the delay network 61, the collector of thetransistor 61a and the collector of the transistor 61k are bothconnected to the conductor 66; however, the transistor 61b is normallynou-conductive due to biasing conditions applied thereto. The emitter ofthe primary current generating transistor 61a is connected to a variableresistor 88. The resistor 88 is manually preset in accordance with thedesired delay and forms a part of a voltage divider including a manuallypreset resistor 89 which reflects the desired duration time. A variableresistor 91, which is connected in circuit with the resistor 88, is acurrent sensing resistor for controlling current in the base circuit ofthe Secondary current generator 61h. As shown, the common junction ofthe resistor 91 with a current sensing variable resistor 92 is connectedto the junction of the lter capacitor 83 and the biasing diode 90. Thiscircuit arrangement establishes biasing and current limiting conditionsfor the circuit 24 such that the conduction of the primary currentgenerator reflects the anticipated system delay characteristics andcontrols the conductive state of the secondary current generator toyield the desired variable speed compensation.

More specifically, the base of the PNP transistor that forms thesecondary current generator 61b, has its base connected to the junctionof the variable resistor 88 and the current sensing resistor 91, and theemitter of this transistor is connetced through a resistor 101 to theoutput of the timing circuit 61e. The timing circuit 61a` is preferablyformed by a pair of transistors 102 and 103 connected in circuit to forma one-shot timing circuit and includes a positive feedback networkformed by diode 104, capacitor 105, and diode 106. The junction of thecapacitor 105 and diode 106 is connected to ground through a iixedresistor 105a and Variable resistor 10511 which, along with capacitor105, partially dictate the timing period for the circuit 61e. i

Emitter biasing potential is supplied to the NPN transistor 102 througha resistor network 107. The base of the transistor 102 is connectedthrough a coupling capacitor 110 and a resistor 111 to the collector ofthe transistor 51h in the rst timer module 48. A diode 114 is alsoconnected to the base of the transistor 102 and functions to provide apathto ground for input pulses supplied to the base of the transistorwhen the switch 84b is in its alternate position as hereinafterdescribed.

Considering now the more detailed operation of the overall controlsystem when the turn-on and turn-olf delay characteristics of the device29` are the same, the aforedescribed normal conductive state of thevarious components prevails until an input signal is supplied for theamplifier 22 to the first timer module 48 through the coupling capacitor47. As previously described, this input signal is an amplified signalrelated directly to the signal produced by the photocell 21a when anarticle interrupts the light source 2lb and photocell.

In response to an input signal, which in accordance with the parametersindicated in the drawings is a negative input signal, the PNP transistor511; is rendered conductive and the transistor 51a is renderednon-conductive. When this occurs, the unijunction 53, in cooperationwith the delay function circuit 26, is conditioned to respond to theoutput of the delay network 61 so as to delay the actuation of theresponsive devices 29 for a period of time necessary to align theadvancing article (or a selected segment thereof) with the device. Morespecifically, when the transistor 51h is rendered conductive the normalpath for collector current through the conductor 66 and through theemitter-base one junction of the unijunction is interrupted. Theinterruption of the current path through the unijunction circuit 53occurs as a result of near ground potential being applied t-o the basetwo junction of this element from a conductor 117 through a resistor53a, the now conductive transistors 5llb and 52, and a diode 116. Inthis connection and as shown in FIGS. 4 and 5, the normal path forcurrent in the collector circuit of the primary current generatingtransistor network 61a (i.e. that is normally completed through theunijunction 53) is shunted by a capacitor bank 94 which, along with itsassociated conductors 95 and 96, defines the delay function network 26.Depending upon the length of delay desired, one of the capacitors of thecapacitor bank 94 `is connected in circuit with the collector of theprimary current generating transistor. Thus, when the multivibrator 51changes conductive states, the timing cycle for the iiring of theunijunction 53 is initiated and will continue until the selectedcapacitor of the capacitor bank 94 has acquired the necessary charge toeffect the tiring of the unijunction.

Since the capacitor bank 94 is actually connected in circuit with thecollectors of both the primary and secondary current generatingtransistors, the charge accumulated therein s related to the conductivestate of each of these transistors. In this connection, the combinedcurrent output of the delay network 61 is initiated as soon as theconductive state of the multivibrator has been altered. That is, whenthe transistor 51b is rendered conductive, a signal is developed at thecollector thereof, and this signal is coupled to the base of thetransistor 102 through the resistor 111 and the capacitor 110. As aresult, the transistor 102 is rendered conductive. Due to the drop inthe voltage at the collector of the transistor 102, the transistor 103is also rendered conductive. Collector current in the transistor 103results in a positive feedback signal being fed to the transistor 102,and this transistor is sent into a more conductive state. It will beapparent that the network formed by the transistors 102 and 103 remainsin a conductive state until Such time as the capacitor 105 has beenfully charged primarily through the timing resistors 105a and 105b.During conduction of the transistor 102 and 103, a voltage is developedat the junction of the resistor 101 and a collector load resistor 121 sothat the secondary current generating transistor 61b is biased intoconduction and remains conductive until the timing circuit 61C concludesits cycle.

In order to effect the desired compensating adjustments in the output ofthe delay portion 61 of the responsive circuit 24, it is necessary toestablish a preselected relationship between the resistor 101, thevariable resistor 91 and the timing characteristics of the circuit 61C.Moreover, in accordance with the present invention, it is preferable toselect transistors of the type indicated so that the current flowing inthe collector circuits of the primary and secondary current generatorsis approximately equal to the respective emitter currents. The voltagedeveloped at the junction of the variable resistor 88 and the resistor91 is directly proportional to the amount of emitter current owing inthe primary current generator 61a. Accordingly, the voltage supplied tothe base of the secondary current generator 61b is proportional to thisemitter current. Moreover, this voltage, dlue to selected relationshipbetween the emitter and collector current values, dictates buildup ofcharge in the capacitor bank 94. Thus, if the resistor 101 is selectedto be approximately one-half the size of the resistor 91, the secondarycurrent generator yields a collector current that is twice the magnitudelof the current supplied from the primary current generator, and thiscurrent component is supplied to the capacitor bank 94 as long as thetiming circuit formed by the transistors 102 and 103 is renderedeffective.

As generally outlined above, the duration of the timing cycle defined bythe capacitor 105, the resistor 105a, and the variable resistor 105b isselected to be less than the minimum delay period that will beencountered in the particular application wherein the system isemployed. Preferably, the variable resistor 105b is adjusted so that theduration of the timing period during which the secondary currentgenerator 6112 provides current to the capacitor bank 94 isapproximately one-half (1/2) the duration of the anticipated delayperiod. Thus, the minimum delay period for the contribution of thesecondary current generator is limited to a timing cycle ofapproximately one-half the delay period, and the magnitude of currentsupplied during this period is approximately twice that which issupplied from the primary current generator, although these parametersare selectively adjustable for any given application.

At the conclusion of the conductive period controlled by the timingcircuit 61C, the primary current generator continues to supply currentto the appropriate one of the capaictors in the capacitor bank 94 untilsuch time as the unijunction 53 is triggered into an alternateconductive state. Since the amount of collector current supplied to thecapacitor bank is directly related to the voltage output of thetachometer generator, compensation is made for any variations in theadvancing rate of the article that occur as the article is advanced fromthe point whereat it is initially detected to a position in alignmentwith the responsive device 29.

When the unijunction 53 is fired due to the build up of the necessarypotential across the capacitor bank 94, the bistable multivibrator isreturned to its normal conductive state. That is, the transistor 51a isrendered conductive and the transistor 51b is rendered non-conductive.The resulting negative voltage that is developed at the collector of thetransistor 51b is supplied to the base of the transistor 56b through acoupling capacitor 131. Accordingly, and as described in theaforementioned copending application, the bistable multivibrator 56 istriggered into an alternate conductive state and the amplifier 57 isrendered conductive. As described in conjunction with the first timermodule 48, the second timer module 49 cooperatively functions with theduration function circuit 27, including a capacitor bank 132, and thenetwork 62 including at least the primary current generator 62a. Thetiming cycle for the firing of the unijunction 58 is thus initiated, andthe amplifier 57 produces an output signal that is supplied through aconductor 59 to a conductor 133 at the input of the solid stateswitching network 28 (FIG. 3).

As long as the control system is functioning in an environment whereinthe turn-on and turn-off delay characteristics of the responsive device29 are equal in duration, only the primary current generator 62acontrbiutes to the buildup of charge in the capacitor bank 132 and,therefore, to the timing cycle of the unijunction 58. In those caseswhere the turn-off delay characteristics of the responsive devicesexceed the turn-on delay characteristics, the switch contacts 78a and77b are closed to bring the secondary current generator 62b into thenetwork 62 along with the timing circuit 62C, both of which circuits areemployed in the responsive circuit 24 in a manner identical to theaforedescribed current generator 61b and timing circuit 61e.

In this connection, the timing characteristics of the timing circuit 62C(i.e. which includes the transistors 141 and 142 and an R-C timingnetwork formed by a variable resistor 143, the resistor 144 and thecapacitor 146) are preset so that the secondary current generator CFI62b is rendered conductive at the outset of the unijunction firingcycle. Similar to the current generator 61b, the secondary currentgenerator 62b supplies an additional amount of collector current to thecapacitor bank 132 during a period equal to one-half the time differencebetween the turn-off and turn-on characteristic of the responsive device29. Preferably, the value of the resistor 148 in the emitter circuit ofthe secondary current generator 62b is again selected to beapproximately onehalf (1/2) the value of the resistor 92. Thus, thenecessary supplementary current is supplied to the capacitor bank 94 toeffect the desired firing of the unijunction 58.

In those instances where the turn-on delay characteristics of theresponsive device exceed the turn-off delay characteristics, thesecondary current generator 62b is not employed, and the switch contact78a is open, although the contacts 77a, 77b and 77C are closed. Thus,the timing circuit 62e is utilized under these operating conditions asis the supplementary shunting network 64. During this mode of operation,the timing circuit 62C compensates for the excessive turn-on time duringthe delay time cycle, Accordingly, and to ensure that the necessaryadjustment is also made in the duration cycle, a portion of the currentderived from the primary current generator 62a during the duration cycleis shunted to the network 64 so that the duration cycle is effectivelyincreased.

In this connection, the conductive state of the network 64 and moreparticularly of the NPN transistor 151 that is employed therein isdictated by the output of the transistor 142. That is, when thetransistor 142 is rendered conductive during the timing cycle of thecircuit 62C, the resulting change in collector potential is supplied tothe base of the transistor 151. This signal is supplied through theclosed switch contact 77C and a resistor 152 which, along with theresistor 153, forms a voltage divider network to provide the necessarybiasing potential at the base of the transistor 151. When the transistor142 is rendered conductvie, the transistor 151 is biased into aconductive state and a path for a portion of the current in thecollector circuit of the primary current generator 62a is provided toground through the closed contacts 77a, the collector-emitter junctionof the transistor 151, and a biasing resistor 156. Irrespective of themode of operation of the responsive circuit 24, under the control of oneor more of the primary or secondary current generating circuits, thedesired duration timing cycle is completed as the unijunction 58 isfired.

Throughout this timing cycle and prior to the unijunction 58 beingrendered conductive, an output signal from the amplifier 57 in thesecond timer module is continuously supplied to the solid state switch28. Referring to FIG. 3, the conductor 133 supplies the signal from theamplifier 57 to an input terminal that is connected to the base of a PNPtransistor 161 in an inverter circuit 162. The transistor 161 isnormally in a conductive state; however, when the amplifier 57 isrendered conductive the input to the inverter circuit 162 causes thetransistor 161 to be cut off. Emitter follower 163 responds to thevariation in the conductive state of the inverter circuit 162 to triggera PNP transistor 164 into conduction. As a result, current ow in thecollector-emitter circuit of the transistor 164 causes the responsivedevice 29 to be rendered effective, and the solid state switchingnetwork 28 remains in this current supplying condition until theunijunction 58 has fired and the amplifier 57 returns to itsnon-conductive state.

As generally outlined above, the responsive circuit 24 can be operatedindependent of the output of the tachometer generator 31 by placing theswitches 84a and 84b in the alternate position. When this is effected,the switch contact 84h precludes either of the timing circuits 61C or62C from being rendered effective since the input pulses which wouldnormally actuate these circuits are now shunted to ground. In addition,the function of the primary current generating circuits 61a and 62a isno longer controlled by a variable output corresponding to the output ofthe tachometer generator but is now dictated by the output voltage ofthe power supply 20. Thus, the delay and duration functions performed bythe circuit are dictated by the settings of the resistors 88, 89, 91 and92.

It will be appreciated that the present invention provides novel meansfor and methods of accurately controlling the actuation of variousresponsive instrumentalities independent of inherent system delayconditions and/ or other variations in system operation. Through theemployment of the coacting primary and secondary current generatingcircuits in the responsive circuit 24, the delay characteristics arereadily compensated for at the initial stage of an operating cycle,effectively as though the delay had been anticipated even prior to theinitiation of a cycle of operation. This feature of the invention canperhaps best be appreciated from a consideration of FIG. 7.

With reference to FIG. 7 and considering the graphically vrepresentedline OAB, this line depicts the build-up of energy necessary to eithertrigger the responsive device or to turn ofi the responsive device afterit has been rendered operative for a preselected period of time.Accordingly, the portion of the curve represented by the line OA depictsthe period of the operating cycle during which both the primary andsecondary current generating circuits of the appropriate network arebeing rendered effective, and the portion of the curve represented =bythe line AB depicts the operation of the system during the remainingportion of the cycle when only the primary current generating circuit isproviding current to the appropriate capacitor bank 94 or 132. Since thesegment of the time base TF indicates the anticipated delay time ofthesystem, it will be seen that the cooperative functioning of the primaryand current generating circuits achieves the same ultimate result in theaccurate build-up of energy within the desired period of time. Thisoccurs as though the build-up of energy had been initiated at thenegative time TF with only the primary current generator contributing tothis energy buildup. The line OCD similarly represents the uniquefunctioning of the system of the present invention at a different speedand under circumstances when the desired energy level is sought to beachieved Within a time period designated by the legend TP2. It is thusapparent that the present invention contemplates a compensated negativetime characteristic to achieve the accurate and reliable actuation ofthe controlled instrumentalities independent of variations in otheroperating conditions within the system.

It will also be appreciated that the foregoing is merely illustrative ofthe invention. Although only a single channel system has been described,it will be apparent to those skilled in the art that multiple, parallelchannels might also be utilized to effectively handle a plurality ofproducts being advanced on a production basis by means of a conveyor'10. Similarly, it will be appreciated that in receptacle fillingapplications, a device comparable to a tachometer generator will beemployed but that the output of this device will be indicative of theflow rate of the product to a stationary receptacle as distinguishedfrom the advancing rate of a receptacle relative to a stationaryresponsive instrumentality. In any event, the systems and methods of thepresent invention have broad applicability to a variety of productionfacilities. Consequently, modifcations in the various system componentsand/ or in their functional relationship to other components necessaryto meet the requirements of various diverse applications would notconstitute a departure from the invention, various features of which areset forth in the accompanying claims.

What is claimed is:

1. A control system for effecting the selective and controlled actuationof a responsive instrumentality, which control system comprises meansfor sensing a preselected system condition, at least one timer control,means for initiating and controlling the operation of said timer controlin response to the sensing of said preselected system condition, saidlast mentioned means including means responsive to fixed system delaycharacteristics and means responsive to variable system conditions so asto effect a compensating variation in the operation of said timercontrol such that the timing cycle of said timer control compensates forsuch lfixed delay characteristics and variable system conditions, andmeans responsive to the initiation and duration of the timing cycledictated by said timer control for actuating a controlledinstrumentality.

2. A control system in accordance with claim 1 in which said initiatingand controlling means comprises primary and secondary current generatingcircuits developing electrical current outputs proportional to saidvariable and said fixed delay characteristics.

3. A control system in accor-dance with claim 1 in which said timercontrol is coupled to the outputs of both said primary and secondarycurrent generating circuits and which said timer control is constructedand arranged `such that its timing cycle is determined by the timeintegrated value of the current outputs of said primary and secondarycurrent generators.

4. A control system in accordance with claim 3 in which said secondarycurrent generator circuit is operated for a predetermined time intervalof shorter duration than the minimum anticipated variable delay and inwhich said lprimary current generator operates for the term of thevariable delay.

5. A control system for effecting the selective actuation of aresponsive instrumentality so that the responsive instrumentality isrendered effective a prescribed period of time after the establishmentof a preselected control system condition and is maintained in anoperative state for a second preselected period of time, which controlsystem comprises means for sensing a preselected system condition, afirst timer control, a first means for initiating and controlling theoperation of said first timer control in response to the sensing of saidpreselected system condition, said first means including meansresponsive to fixed system delay characteristics and means responsive tovariable system conditions so as to effect a compensating variation inthe operation of said first timer control such that the timing cycle ofsaid `first timer control compensates for such fixed` delaycharacteristics and variable system conditions, a second timer control,a second means for initiating and controlling the opertion of saidsecond timer control upon the termination of the timing cycle controlledby said `first timer control, and means responsive to the initiation andduration of the timing cycle dictated by said second timer control foractuating a controlled instrumentality, said second means includingmeans responsive to the fixed system delay characteristics and meansresponsive to variable system conditions during the operation of thecontrolled instrumentality for effecting a compensating variation in theoperation of said second timer control.

6. A control system in accordance with claim 5 wherein said system is anelectronic control system and wherein said first and second timercontrols are electronic timer modules each of which includes a bistablemultivibrator connected in circuit with a unijunction firing circuit.

7. A control system in accordance With claim 6 and wherein said firstand second circuit means each includes dual primary and secondarycurrent generating circuits, the combined output of which dictates theduration of said timing cycles.

8. A control system in accordance with claim 7 and wherein said dualcurrent generating circuits are interconnected such that said primarycurrent generator produces an output related to the variable systemconditions and said secondary current generator produces an output 15related to both the fixed system delay characteristics and the outputfrom said primary current generator.

9. A control system in accordance with claim 8 and wherein said firstand second circuit means also include timing circuits connected incircuit with said secondary current generators 'so that the secondarycurrent generators produce an output signal during only a preselectedinitial portion of the timing cycles.

10. A method of controlling the selective operation of a responsiveinstrumentality under conditions such that the operation of saidinstrumentality is subject to fixed delay operating characteristics andother variable operating conditions, which method comprises establishingan operating cycle for said responsive instrumentality in accordancewith the function to be performed thereby7 initiating said operatingcycle, compensating for both said fixed delay characteristics and saidvariable operating conditions that aiect the operation of saidinstrumentality only during the initial portion of said operating cycle,and compensating only for said variable operating conditions during theremaining portion of said operating cycle such that the selectiveoperation of said responsive instrumentality is reliably controlled.

11. A method in accordance with claim 10 wherein the initiation of theoperation of said responsive instrumentality is delayed for apreselected period of time after the References Cited UNITED STATESPATENTS 2,374,779 5/ 1945 Preston 328-75 X 3,212,377 10/1965 Bennett328-5 X 2,903,584 9/1959 Jaffe et al. 328-185 2,928,003 3/1960 Etter328-185 X 3,364,366 1/1968 Dryden 328-185 X 20 DONALD D. FORRER, PrimaryExaminer S. D. MILLER, Assistant Examiner U.S. Cl. X.R.

Patent No.

Inventor-(s) Pfl-105D UNI'LED 5'1/ Tief; www 'l Oruro CERTFICATE GFGORRECFIGN FRANK's. KASPER Dated December 7, 1970 It: is certified thaterror appears in the above-identified pc'font and that said LettersPatent are hereby corrected as shown below:

Column 3, line l -A vafter "lll" insert the following:

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I, FEB; `2 ,j197'1 n Attest: l l

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